There has been known a persistent scheduling for controlling a radio resource allocation periodically in order to allocate the radio resources to a transmission packet of a first transmission.
The persistent scheduling is expected to be applied mainly to voice communications, such as VoIP.
This is because the persistent scheduling can allow a reduction in the overhead of a control channel used for notifying an allocation of the radio resource, and thus the persistent scheduling is suitable for communications in which packet are arrived at certain intervals and which are performed at a low rate.
On the other hand, a field that stores speech information is provided in an RTP (Real-time Transport Protocol) payload format used for transmitting speech data in an adaptive multi-rate (AMR) method or an adaptive multi-rate wide band (AMR-WB) method.
The speech information includes a speech frame or a comfort noise frame. From this field, a talk-spurt period or a silent period can be detected (for example, see Non-Patent Document 1).
Generally, in the voice communications, it is often the case that, when one side is speaking, the other side is in a silent state.
When considering a case in which the radio resource allocated to a specific mobile station by the persistent scheduling is temporarily released when the specific mobile station is in such a silent state, and such radio resource is allocated to another mobile station. In such case, a statistical multiplexing effect which achieves an efficient use of a fixed channel capacity can be expected. This also leads to an effective utilization of the radio resource.
However, neither a radio base station (eNB: evolved Node B) nor a mobile station (UE: User Equipment) becomes aware that an audio codec detects a talk-spurt/silent period in an application layer.
Thus, in order to release the radio resource based on whether the state is the talk-spurt state or the silent state, the radio base station or the mobile station needs to be notified of the detection of the silent state (for example, in an MAC layer), or to presume the detection of the silent state.    Non-Patent Document 1: RFC3267, Real-Time Transport Protocol (RTP) Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codec